Red yeast rice, also known as red mold rice, is a fermented product of the fungus Monascus purpureus (also known as red yeast or red mold), using rice as a feedstock. Red yeast rice has been used in ethnomedicine for thousands of years in China and elsewhere in Asia. Secondary metabolites of Monascus fermentation include monacolin K (also known as lovastatin), gamma-aminobutyric acid (GABA), the antioxidant dimerumic acid and a variety of pigments.
Monacolin K is produced by at least 17 of the 124 known Monascus strains; among these are M. ruber, M. purpureus, M. pilosus, M. vitreus, M. pubigerus, and M. anka. This compound inhibits cholesterol biosynthesis and is also known to regulate inflammatory and immunological responses, coagulatory processes, bone turnover, neovascularization, vascular tone, and arterial pressure.
GABA, which acts as an inhibitory neurotransmitter in mammals, is antihypertensive, diuretic, and tranquilizing. It further regulates blood pressure, heart rate, sensations of pain and anxiety, and lipid levels in serum and can prevent diabetes and inhibit cancer cell proliferation. GABA supplementation has been demonstrated to calm and de-stress animals such as race horses when they are subjected to, for example, crowding situations.
Pigments produced by Monascus include rubropunctamine, monoscorubramine, monascin, ankaflavin, rubropunctain, and monascorubin; new Monascus pigments are still being discovered. These pigments impart color and have been reported to possess immunosuppressive, antioxidant, antibiotic, antimalarial, antitubercular, and antitumor properties.
The health benefits of many of the above-listed secondary metabolites are well-studied. Treatment with red yeast rice has been shown to suppress atherosclerosis in both mammalian and avian models. Poultry that are given feed supplemented with red yeast rice produce meat with lower cholesterol and higher levels of unsaturated fatty acids, and produce eggs with lower cholesterol levels.
While the mycotoxin citrinin produced by Monascus is reported to be nephrotoxic, the practice of feeding Monascus-fermented products to animals is generally recognized as safe. Additionally, fermentation can be optimized to reduce or eliminate the production of citrinin and/or other toxins.
Solid state fermentation has been employed to produce monacolin K from Monascus cultures; yields vary based on type of substrate, type of fermentation, and growth conditions. Mixed fermentation with other microbial species has been demonstrated to lead to increased pigment production.
Dried distillers grain with solubles (DDGS) is produced from whole stillage, a co-product of corn ethanol fermentation. Production of DDGS is expected to rise with increasing demand for biofuels. DDGS has found use primarily as animal feed, particularly for cattle, swine, poultry, and in aquaculture. In the US, DDGS production was 39.27 million short tons for 2012-2013; this number is projected to rise to 41.23 to 43.78 million short tons for 2013-2014.
While red yeast rice powder or microbial cultures have been used to supplement animal feeds in the past, these products have the disadvantage of being difficult and expensive to produce. First, a Monascus species must be cultivated in order to produce desired secondary metabolites. Then, the yeast culture must be processed in order to extract and purify the metabolites. Extraction and purification must be completed for each metabolite to be added to the feed. Finally, the metabolites must be added to an existing animal feed product. These extra processing steps add time and expense and, ultimately, add cost to the final feed products that are produced. Moreover, rice is a staple human food in many countries and its use for Monoascus fermentation will negatively impact human food supply. Thus, it would be desirable to eliminate some of the steps currently used to produce nutraceutically-enhanced animal feeds in order to save costs. Ideally, these feeds could be used with a variety of livestock and non-livestock animals for the purpose of enhancing the health of the animals and/or increasing the nutritional and health qualities of products produced by the animals (i.e., meat, eggs, dairy, and/or poultry). Further, it would also be desirable to provide a new source of and method for extracting nutraceuticals to be used as food supplements, additives, and/or medicines for humans and animals. Finally, if a new market could be developed for existing biofuel co-products and wastes, the long-term sustainability of biofuels could be ensured. The present invention addresses these needs.